The research proposed will empoly a new method to study short-lived complexes in solution Nuclear relaxation times arising from the coupling of solvent molecules with paramagnetic species (spin labels) will characterize the dynamics of intermolecular interactions on the 10-8 to 10-11 second time scale. The experimental program will: 1) complete the testing of the instrumental method that has been developed; 2) apply the method to determine the time scales and distances that characterize hydrogen bond formation; 3) identify the role the atoms away from complexation site have on the characteristics of hydrogen bonds; and 4) examine the molecular dynamics of solvation in solutions in which competition for spin probes by several hydrogen bond-forming solvents is present. The goal is to determine the rates of forming and breaking these bonds between solvent and solute, and to isolate the parameters that effect changes in bonding strength and dynamics. Interactions such as hydrogen bonding are extremely significant in physical chemistry and health-related sciences because they determine the nature of liquids in general and the specific properties of the systems under investigation.